Classifications

• • D—TEXTILES; PAPER
  • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
  • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
  • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
  • D02G3/02—Yarns or threads characterised by the material or by the materials from which they are made
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S57/00—Textiles: spinning, twisting, and twining
  • Y10S57/903—Sewing threads

Definitions

• Acrylic yarns suitable for use as sewing thread, cord or twine, or for further processing into sewing thread or cordage, and having an acceptably high tenacity, with minimally acceptable qualities of fibrillation and elongation, are produced by spinning staple acrylic fibers of generally low tenacity and high elongation into yarn of generally low tenacity, and by substantially stretching the spun yarn under thermal conditions.
• This invention relates to a process for the production of acrylic yarns suitable for use as thread, sewing thread, cord or twine, or for further processing into sewing thread, cordage and the like; and more particularly, to a process for imparting high tenacity and low elongation to yarns from acrylic staple fibers and to the product thereof.
• the spun yarn is made from low tenacity high elongation staple of a quality such as to resist breakage during the spinning process, it is of insufficient tenacity and of excessive elongation to provide a satisfactory finished product of sewing thread, or cordage.
• those qualities of acrylic fiber which are consistent with efiicient yarn spinning processes are inconsistent with the use of the spun yarn for sewing thread or cordage.
• Another object of this invention is to provide yarns of acrylic fiber having tenacity and elongation qualities suitable for use as thread, sewing thread, cord or twine, or for use in further processing into sewing thread of cord age products generally.
• acrylic fibers fibers produced from acrylonitrile polymers.
• acrylonitrile polymer polyacrylonitrile, copolymers and inter polymers of acrylonitrile, and blends of polyacrylonitrile and copolymers of acrylonitrile with other polymerizable mono-olefinic materials, as well as blends of polyacrylonitrile and such copolymers with small amounts of other polymeric materials, such as polystyrene.
• acrylic fibers produced from acrylonitrile homopolymers and copolymers, with variations and blends, as described generally above, are suitable for use in ac cordance with this invention.
• acrylic fibers may be manufactured by wet spinning of acrylonitrile polymers from organic solvent solutions. The method briefly entails dissolving the acrylonitrile polymer in a suitable organic solvent or inorganic salt solution to produce a spinning solution, extruding the spinning solution through a multiorifice spinning jet into a coagulating bath to form a plurality of filaments, washing the filaments to remove residual solvent, drawing the filaments to achieve molecular orientation, and finally drying the washed filaments to remove moisture.
• the fibers may also be produced by dry spinning wherein the solvent is removed from the spinning solution by evaporation.
• the acrylic staple fibers suitable for conventional yarn spinning and for heat stretching in accordance with this invention preferably have a denier from about 3 to 25 per filament, and a staple length from about 1 to 8 inches.
• 15 denier filaments possess a good balance of physical properties, are easily spun into yarn on conventional woolen or worsted textile machinery, and function well in the practice of this invention. Staple of 25 or higher denier may also be used if care is taken in the operation of the yarn spinning apparatus.
• lower denier fibers may be converted into yarns on either woolen or cotton processing machinery using conventional techniques.
• Fiber staple length is necessarily determined by the method selected for yarn spinning, and may vary from about 1 inch up to about 10 inches. In a preferred embodiment of this invention, wherein 15 denier fibers are spun to yarns on worsted equipment, the preferred staple length is from 3 to 8 inches.
• Thread, sewing thread, cords, twine and cordage products generally are of an infinite number of varieties and involve many different processes and combinations thereof. Volumes have been written on the subject. Thread, as used herein, means a slender strand or strands of a specialized type of yarn used for some particular purpose such as basting, sewing, darning, embroidery work, etc. Commonly it is a cord made of two or more yarns twisted or plyed and then finished for a definite purpose.
• Cordage as used herein, is a general term which includes banding, cable, cord, rope, string, and twine made from fibers.
• twine is an aggregate of parallelized fibers or yarns compacted into a twisted structure of continuous length, 'which is used essentially for tieing or binding.
• cord as used herein means an aggregate of yarns braided or twisted into a structure of continuous length, generally less than in diameter, with a compacting of fibers and a structural balance to maintain compactness.
• Rope is a flexible, twisted yarn-strand structure, usually greater than A in diameter, structurally balanced to maintain compactness.
• the above described heat stretching of yarns may or may not result in the finished product.
• the heat stretching step may well be the ultimate step in the production of a sewing thread or twine. It may be the penultimate step in the production of a thread and followed by a finishing step. Or it may be, as in the production of rope, that the heat stretched acrylic yarn may be subjected to yet further twisting and plying, as well as finishing steps, in the preparation of the end product.
• these fibers have a tenacity range of from about 1.7 to 2.4 grams per denier and an elongation range of from about to 45 percent.
• the yarns obtained from these fibers are usualiy of low to medium tenacity, or within a tenacity range of from 1.2 to 1.5 grams per denier, and have a relatively high elongation of 20 to percent.
• the thermal stretch employed in accordance with the instant invention may be a dry heat stretch or a steam stretch, the latter being preferred, having been observed to produce slightly superior results.
• Yarn temperature may vary from about 86 C. to about 235 C. Preferred begin to thermally degrade or to assume a tacky composition. The preferred temperature range is from safely above the second order transition temperature to safely below the thermal degradation temperature. These temperatures, while critical, are not finite; and it can only be said with respect to the full range that it is a conservative operable range for the heat stretch, but that slight variations below the stated minimum or above the stated maximum will not necessarily yield patently unacceptable results.
• Permissible variations of heat exposure time and distance need only conform to the stretch capacity of the particular filament involved and lend the heat stretch process of this invention well to a continuous process whereby heat is applied in a tube through which the fibers move continuously, the fiber entry speed being slower than the fiber exit speed.
• the amount of stretch imparted in accordance with this invention may be as much as 70%. However, stretch ratios as low as 1.20 have produced acrylic twines of acceptably high tenacity and low elongation.
• EXAMPLE I A 4 ply twine of 2/ 1 cc. acrylic spun yarn of 15 denier per filament, cut to a 6" staple, with S twist at 6 turns per inch and with a steam setting on the twist was subjected to a heat stretch in accordance with this invention.
• the acrylic fiber initially produced from a copolymcr containing 93% acrylonitrile and 7% vinyl acetate, was cut to staple and spun on a worsted system in accordance with the figures shown in the left column. Elongation, breaking strength and tenacity, as shown in the third, fourth and fifth columns are the results of standard tests run on the cord after heat stretching.
• EXAMPLE II The 15 denier acrylic staple described in Example I was spun on the worsted system and plied into a sample having a nominal yarn count of 3.5/4. This yarn was hot stretched as shown at various stretch ratios to obtain the properties shown.
• temperatures are from C. for steam stretching to about C. for dry heat stretching.
• the temperature range of 86 to 235 C. reflects a minimum below which there is an unacceptable amount of fiber breakage during the stretch, and a maximum above which the first stages of fiber decomposition begin to appear; that is, the fibers Thermal stretch conditions Control, 3.5/4 cc.
• the twine produced according to the preceeding examples although entirely satisfactory for its intended use, was found to have high boiling water shrinkage. For many applications, such as sewing awnings, sandbags, and the like, this shrinkage is of no consequence. Where application is such that the sewn article is to be subjected to elevated temperatures such as in washing and drying operations, the acrylic twine may be heat set at elevated temperatures, preferably above 150 C., in order to reduce the potential shrinkage of the yarn and thereby avoid puckering seams.
• the preceeding examples illustrate a preferred embodiment of the present invention employing high denier acrylic fiber. It is contemplated that other deniers and acrylic fiber compositions other than that specifically described may be similarly processed with equally efiective results, and such fibers are considered with the broad scope of the present invention.
• a process for the production of acrylic yarns of sufiiciently low elongation and sufiiciently high tenacity for use as thread, sewing thread, cord and twine and in cordage products comprising the steps of spinning acrylic staple fibers into a yarn, heating said yarn and concurrently stretching said yarn from about to about 70%.
• Sewing thread comprised of acrylic staple fibers, said thread having a minimum tenacity of about 1.6 grams/denier and a maximum elongation of about 20%.
• Cordage comprised of acrylic yarn having a minimum tenacity of about 1.6 grams/ denier and a maximum elongation of about 20 percent.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Textile Engineering (AREA)
• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=24835580

Family Applications (1)

Country Status (2)

Cited By (1)

Citations (7)

• 1968
  • 1968-02-16 US US705946A patent/US3492805A/en not_active Expired - Lifetime
• 1969
  • 1969-02-17 BE BE728527D patent/BE728527A/xx unknown

Patent Citations (7)

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